Insect pests are a worldwide problem, often causing damage to cultivated crops and plants. Thrips, comprising the order Thysanoptera, are one common insect pest. By feeding on flowers and leaves, and laying their eggs within the plant, thrips can cause serious damage to crops. Some thrips also spread plant damaging viruses.
A thrips infestation can be hard to detect, especially at low densities, as the insects are often active within the enclosed parts of a plant such as the buds. This also makes them difficult to reach with pesticides. In addition, environmental concerns mean that it is becoming less desirable to use pesticides to control insect populations, and many species of thrips are becoming resistant to pesticides. Thus, there is an ongoing need for methods that monitor thrips at low densities, and alternative methods of controlling thrips, in order to lessen the potential for damage to cultivated crops and plants.
It has been proposed that scent may be used by thrips for detection of and orientation to their hosts. Thus, certain aromatic compounds can act as attractants and/or arrestants for thrips. It is therefore possible to lure the insects using suitable traps baited with attractant compounds.
Repellant compounds may also protect crop plants, particularly if used with separate traps baited with attractant compounds.
Ethyl nicotinate is a potent attractant for Thrips obscuratus (D. R. Penman, G. O. Osborne, S. P. Worner, R. B. Chapman and G. F. McLaren, Journal of Chemical Ecology, (1982) 8, 1299). These thrips are attracted to ripe peaches, but ethyl nicotinate is even more attractive to the insects than ripe fruit. Ethyl nicotinate is less attractive to Frankliniella occidentalis and varied in its attractiveness to Thrips tabaci (Teulon, D. A. J., Penman, D. R. and Ramakers, P. M. J. (1993) J. Econ. Entomol., 86, 1405-1415).
A number of other aromatic compounds have been reported as attractants for various thrips species. For example, anisaldehyde, in combination with blue sticky traps (H. F. Brødsgaard, WPRS Bull. (1990) XIII, 36) or yellow water traps (Teulon, D. A. J., Hollister, B. and Cameron, E. A. (1993) IBOC/WPRS Bull., 16, 177-180), is an attractant for Frankliniella occidentalis. Anisaldehyde varies in its attractiveness to Thrips tabaci (Teulon, D. A. J., Penman, D. R. and Ramakers, P. M. J. (1993) J. Econ. Entomol., 86, 1405-1415) and is an attractant for Thrips hawaiiensis but not for Thrips coloratus (T. Murai, T. Imai and M. Maekawa, Journal of Chemical Ecology, (2000) 26, 2557).
In field trials, methyl anthranilate has been shown to be an attractant for Thrips hawaiiensis and Thrips coloratus, but not for Thrips tabaci (T. Mural, T. Imai and M. Maekawa, Journal of Chemical Ecology, (2000) 26, 2557). Furthermore, ethyl anthranilate is an attractant for Thrips hawaiiensis, Thrips coloratus, and Thrips flavus (T. Imai, M. Maekawa and T. Mural, Appl. Entomol. Zool. (2001) 36, 475).
Decyl acetate and dodecyl acetate have been reported as alarm pheromones of Frankliniella occidentalis with repellant activity (K. M. MacDonald, J. G. C. Hamilton, R. Jacobson and W. D. J. Kirk, Entomologia Experimentalis et Applicata (2002), 103, 279). These compounds have been combined with insecticides to control field infestations of Frankliniella occidentalis (D. F. Cook, I. R. Dadour and W. J. Bailey, Int. J. Pest Management (2002), 48, 287).
JP Patent 48006537 describes an apparatus containing the attractants anisaldehyde and(or) cinnamaldehyde used to trap and kill insects such as thrips.
JP Patents 02049703, 01261303 and 01038003 describe respectively eugenol and/or beta-ionone, cinnamic aldehyde and/or o-methoxycinnamic aldehyde, or thiazole derivatives as repellants for thrips, especially against Thrips palmi. 
WO 03/055309 describes a method of surveying or controlling thrips using behaviour modifying compounds. Monoterpene esters were shown to be attractive to Frankliniella occidentalis by testing in a Y-tube olfactometer, rather than in field trials.
It is an object of this invention to provide a method for controlling, surveying or regulating thrips or to at least provide the public with a useful choice.